Surface architecture decoration on enhancing properties of LiNi0.8Co0.1Mn0.1O2 with building bi-phase Li3PO4 and AlPO4 by Al(H2PO4)3 treatment

Abstract As a promising cathode material, LiNi0.8Co0.1Mn0.1O2 has merits of relatively low cost and high discharge specific capacity, but its shortcoming of poor cycle stability restricts its extensive application. To improve the electrochemical performance of LiNi0.8Co0.1Mn0.1O2, Al(H2PO4)3 is used for surface treatment. Al(H2PO4)3 can react with residual lithium on the surface of LiNi0.8Co0.1Mn0.1O2 to build bi-phase Li3PO4 and AlPO4 coating layer (abbreviated as “LNCM@ALP”). This co-coating layer with good Li+ conductivity and chemical stability against the electrolyte, which significantly improved the cycling stability and rate performance of the material. Based on a series of characterization methods, it is proved that bi-phase Li3PO4 and AlPO4 coating layer co-exist on the surface of LiNi0.8Co0.1Mn0.1O2, and stabilize the structure of surface-modified sample LiNi0.8Co0.1Mn0.1O2. The electrochemical test has shown the cycle and rate performance of the LNCM@ALP sample has been significantly improved. After 100 cycles, the capacity of 0.5wt% co-coated LNCM@ALP decreases from 182.8 mAh g-1 to 167.8 mAh g-1with the retention rate of 91.79% compared with bare LiNi0.8Co0.1Mn0.1O2 of only 82.66%. And at the discharge capacity of 0.5wt% coated-samples are 162.5 mAh g-1 and 150.2 mAh g-1 at 5C, 10C, which shows an excellently rate performance.